135 hp balck max oil inj.(over haeting)

[shockers_united]

ok we own a 1987 black max oil injected mercury. mounted on a 18 foot wellcraft deep v hull. now the problem is, it over heats every time we get to close to wide open or from riding long distances. we have replaced the pump, temp gauges eveything we can think of, water goes in just fine and comes out. but it still over heats. we can't fish off the stern sometimes cause we burn ourselvs. the paint on the moter is blistered. and we can't think of what else to do. i need to know is this a common problem, and any sugestions of how to fix it. we don't want to sell cuase it's a great boat we put in a lot of work to restor it (last owner left it sitting in the gulf [dirtiest water ever] never used it or even covered it) any sugestions

 

[Chris1956]

Re: 135 hp balck max oil inj.(over haeting)

OK - The cooling system is complsed of the waterpump in the lower unit, two thermostats, a poppit valve and the water passages. First check the water intake holes on the gearcase. Are they clear? I have gotten barnacles inside the lower unit, which blocked the flow of water. Did you replace the thermostats? How about the poppit?

If that motor is overheating enough to blister the paint, you need to fix it right now, or you will need to junk it. You may need to pull the cylinder heads and inspect the cooling water passages.

 

[rndn]

Re: 135 hp balck max oil inj.(over haeting)

Ditto to the above post, and welcome to the forum. You do not want to drive the motor if it is overheating enough to blister the paint.

 

[CharlieB]

Re: 135 hp balck max oil inj.(over haeting)

Curious if anyone has changed the prop?

What prop is on it?

Has anyone pulled off the powerhead and checked to see if the base gasket is leaking cooling water into the exhaust? Or if the passages are restricted from running into a sand bar? or mud!

 

[shockers_united]

Re: 135 hp balck max oil inj.(over haeting)

well a i already said water goes through it i put my hand through the water while it was idling and i burned the **** out my self. so i son't think it is clogged. right now we are doing a complete rebuild of the lower unit(were the pump is. and see the wierd thing is the blistering isn't happening by the heads gut off to the rear where there is nothing to over heat the blistering is also worse on the left

 

[shockers_united]

Re: 135 hp balck max oil inj.(over haeting)

Curious if anyone has changed the prop?

What prop is on it?

Has anyone pulled off the powerhead and checked to see if the base gasket is leaking cooling water into the exhaust? Or if the passages are restricted from running into a sand bar? or mud!

i thougyt water was supposed tyo come out of the exhoust and as far asi know the prop is the orig. we gut it second hand and hell if i know what the previus owner did

 

[j_martin]

Re: 135 hp balck max oil inj.(over haeting)

well a i already said water goes through it i put my hand through the water while it was idling and i burned the **** out my self. so i son't think it is clogged. right now we are doing a complete rebuild of the lower unit(were the pump is. and see the wierd thing is the blistering isn't happening by the heads gut off to the rear where there is nothing to over heat the blistering is also worse on the left

That water should be uncomfortably hot, but not scalding. If passages were partially plugged, it would overheat like that.

Something is seriously wrong. It won't live long like that. Could be anything from a wrong or inverted gasket on the water pump, or engine base, to a bad head gasket, to plugged passages in the motor.

hope it helps.
John

 

[seabasser]

Re: 135 hp balck max oil inj.(over haeting)

have you checked where the water tube goes in to the bottom of the powerhead the seal will get corrosion around it and swell shut.

 

[Chris1956]

Re: 135 hp balck max oil inj.(over haeting)

Shockers, It sounds like it gets hot between the cylinder heads. If that is true, it would seem that the water that is supposed to cool the exhaust, isn't making it to the exhaust. It sounds like you need to pull the exhaust covers and heads to see why!

 

[shockers_united]

Re: 135 hp balck max oil inj.(over haeting)

Shockers, It sounds like it gets hot between the cylinder heads. If that is true, it would seem that the water that is supposed to cool the exhaust, isn't making it to the exhaust. It sounds like you need to pull the exhaust covers and heads to see why!

no the blistering of the paint is right under the carbs

 

[Chris1956]

Re: 135 hp balck max oil inj.(over haeting)

OK - You got me on that one. Is the midsection getting warm? The only way I could see the paint under the carbs getting hot is if the exhaust was not cooled at all before it hit the midsection. I still thing you should pull the exhaust covers and see wha *** looks like.

 

[shockers_united]

Re: 135 hp balck max oil inj.(over haeting)

ok well we shoved a hose up the water intake with the lower unit off. and blasted water up through to blow out a clog. the water coming out isnt as hot now when i put my hand in but we will see when we take it out. the thing that puzzles me is that none of the wires nere the blistering is destroyed melted or anything